Back in the early 1990s, a housemate of mine once got into such a strop that he stayed in his room for an entire weekend. When he finally emerged his first question was, "Is that Bryan Adams song still number one?"

For most of this decade, golf has been a bit like that.

A moody student could have locked himself into his room in August 1999 and stayed there for five years and three weeks without missing a thing.

But one week later and golf's answer to the Canadian power ballad had been toppled. Tiger Woods was no longer number one, and possession of golf's top spot was up for grabs once again.

Fast forward eight months and the balance of power is more keenly poised than ever.

Woods might not be back to his imperious best, but two victories already this season suggest the 29-year-old is not far off.

THE MAJORS CHART

1 Mickelson (1, 2, 3, T6), 12

2 Els (2, T9, P2, T4), 17

3 Singh (T6, T28, T20, 1), 55

4 Woods (T22, T17, T9, T24), 72

Results in the 2004 majors, final score is cumulative total of finishes

And he will need to be if he is to get the genies of Ernie Els, Phil Mickelson and Vijay Singh back into their bottles.

Reinvigorated by evidence of Woods' mortality, this trio raised their games to give fans what they had been crying out for: a contest to match the sport's most famous rivalries.

A quick glance at the world rankings (as illustrated by the graph above) reveals just how the fortunes of these four have become locked together.

The rankings are based on a two-year rolling cycle. More recent results are given greater weight, but good performances from two seasons before can bolster a fading player.

The statistics also try to take into account the relative merits of each victory. So, for example, a major is worth 50 ratings points, while wins on the European or US tours will bring a minimum of 12 points.

A player's total points for two years are then added up and divided by the number of events they have played.

At the end of 2000, the three-quarter mark for Woods' unprecedented "Tiger Slam", the American prodigy had an equally unprecedented 17-point lead over his nearest rival at the top of the rankings.

That lead was six points a year later, and up to eight again - thanks to two more majors - by the end of 2002.

THE SCORING CHART

1 Singh, 68.84

2 Els, 68.98

3 Woods, 69.04

4 Mickelson, 69.16

2004 PGA Tour scoring averages

But the last two years have seen Woods' lead slip away to the extent that he was passed by first Singh and then Els in 2004.

When this happened the rankings were only confirming what everybody in golf had known for a long time: the Tiger years are over, welcome to the Big Four.

That Woods, whose scoring average in 2004 was one-and-a-half shots worse than in 2000, has since clawed his way back to the top is proof that he has started hitting fairways again, and is indicative of his tenacity.

It will not, however, have concerned Els, Mickelson and Singh too much.

Mickelson, thanks to a storming year in the majors in 2004 and two Tour wins this year, is the chart's biggest climber over the last 12 months. His points average has risen by four, while Woods is two-and- a-half points down on 12 months ago.

The left-hander's form in the big events last year was awesome, with the high point coming at Augusta.

But, in the debit column, the 34-year-old American still has not beaten Woods in a final-round head-to-head. The defeat at Doral in March was just the latest in a growing list of second-bests to his great rival.

Singh, the big gainer in 2004 thanks to his nine-win season, is a point better off than average a year ago. But the Fijian veteran is nearly two points off the high-water mark of his fortunes in 2004.

Els' status is even harder to fathom as he continues to play his own, highly itinerant, schedule. Like Woods and Mickelson, the 35-year-old South African already has two wins in 2005, but his came in the Middle East.

What is certain is this. Woods, whose last major title came 10 attempts ago, will never again take such a stranglehold on the rankings.

And just as today's pop charts see a new number one almost every week, expect to see golf's top ranking become sport's hottest potato.